﻿#include"Stack.h"

// 初始化栈
void STInit(ST* ps)
{
	assert(ps);
	ps->arr = NULL;
	ps->capacity = ps->top = 0;
}

// 销毁栈
void STDestroy(ST* ps)
{
	assert(ps);
	if (ps->arr)
	{
		free(ps->arr);
	}
	ps->arr = NULL;
	ps->capacity = ps->top = 0;
}

// ⼊栈
void STPush(ST* ps, STDataType x)
{
	assert(ps);
	if (ps->capacity == ps->top)
	{
		int newcapacity = ps->capacity == 0 ? 4 : 2 * ps->capacity;
		STDataType *tmp = (STDataType* )realloc(ps->arr, newcapacity * sizeof(STDataType));
		if (tmp == NULL)
		{
			perror("realloc fail!");
			exit(1);
		}
		ps->arr = tmp;
		ps->capacity = newcapacity;
	}
	//空间足够
	ps->arr[ps->top++] = x;
}

//出栈
void STPop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));

	--ps->top;
}

//栈是否为空
bool STEmpty(ST* ps)
{
	assert(ps);
	return ps->top == 0;
}

//取栈顶元素
STDataType STTop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));

	return ps->arr[ps->top - 1];
}

//获取栈中有效元素个数
int STSize(ST* ps)
{
	assert(ps);
	return ps->top;
}
